1. Field of the Invention
The present invention relates to apparatuses for propelling elongated devices including a sharp object, such a hypodermic syringe and needle or the like, into biological tissue, and more particularly to means of facilitating the assembly of such an apparatus and means for adapting such an apparatus for use in conjunction with a conventional lancet for taking of blood samples or the like.
2. Description of the Contemporary and/or Prior Art
The psychological as well as physiological trauma associated with the injection of therapeutic substances into living bodies by way of the needle of a hypodermic syringe or the like and the puncturing of biological tissue to take blood samples is well known to anyone experiencing or delivering such procedures. Furthermore, for patients which must self-inject themselves, such as diabetics who undergo continuous insulin therapy, and have only a limited number of sites into which insulin can be injected because of the limits of the patient's reach during self-injection, the shortcomings of an unadorned conventional hypodermic syringe are also well known. For example, it is quite difficult for a diabetic to self-inject into the normal injection site on the upper portion of the arm because of the inconvenience of reach. Therefore, it has long been desirable to provide an apparatus which will aid a diabetic in self-injection.
It is also desirable, especially in injecting children, to camouflage the hypodermic syringe so that the presence of the needle thereof is not overwhelming. Additionally, pain can be minimized if insertion of a hypodermic needle is quick and even, a set of circumstances which are not always obtainable under direct human control. Furthermore, since it is frequently necessary for family members who are unskilled in injection techniques to inject patients, it is quite desirable to have an automatic injector which holds a conventional hypodermic syringe and which, upon release, quickly causes the needle of the hypodermic syringe to be propelled into biological tissue so that therapeutic fluids can be injected.
Prior attempts to produce such automatic devices are known but unfortunately these devices have failed, not because of their performance when they worked, but because of design flaws which caused malfunctions and jamming. Especially in a medical apparatus, reliability and repeatability of function is of primary importance and therefore such previously known devices have not enjoyed widespread use.
Illustrative of prior art devices is that disclosed in U.S. Pat. No. 2,664,086 issued to G. O. Transue on Dec. 29, 1953. Another similar apparatus is discussed in the Journal of the American Medical Association, Apr. 14, 1956, page 1308, in an article entitled "A New Injector Designed to Minimize Pain and Apprehension of Parenteral Therapy" by Figge and Gelhause.
A further prior art apparatus is illustrated in FIGS. 10, 11, and 12 of the present application. All of these apparatuses basically include a member for holding the syringe and means for shifting the syringe out of a housing upon release of the engagement of the syringe holding element and the housing. Engagement and temporary locking of the elements of these apparatuses has been accomplished by use of ball bearings which engage recesses and apertures in the elements of these apparatuses. In some instances the ball bearings have been placed in position by deformation of the elements and forcing of the ball bearings into position, aided by sloppy tolerances of the elements. In other instances, such as the apparatus illustrated in FIGS. 10-12 of the present application, insertion of the ball bearings have been accomplished through the boring of a ball bearing delivery aperture in a selected element. The ball bearings are positioned by placement through this aperture and the plugging of the aperture after insertion of the ball bearings. This has not proven to be satisfactory since the plugged aperture presents a weak spot in the assembly and, if the plug either extends too far or not enough in the aperture, it can be cause for jamming of the apparatus. While such jamming can be rectified, it is not a very pleasant situation if it takes place during the process of injection by the apparatus.
The present invention overcomes the shortcomings associated with the prior art by providing a configuration of elements which permits assembly without the deformation of any of the elements of the invention or the boring of a ball bearing delivery aperture. Therefore, the present invention avoids the jamming problems associated with the prior art.
Another procedure which requires the piercing of a patient's skin by a sharp object is in the use of a lancet for piercing a fingertip or other site to obtain a drop of blood for blood testing. While such a procedure may only be an occasional nuisance for most patients, some patients, such as certain diabetics, must test their blood numerous times during the day for certain types of therapy. For instance, the diabetics undergoing this particular type of therapy may have to pierce their fingertips or other sites as many as four times a day. The trauma associated with this process is not insignificant and the importance of making a quick and clean puncture is magnified. Apparatuses are known in the prior art for forcing the point of a lancet into a fingertip or the like by mechanical means. For instance, a device is marketed by Ulster Scientific under the trade name Autolet. The Autolet apparatus engages a lancet in a spring loaded member which is released by pushing of a trigger, this release propelling the sharp point of the lancet into a selected tissue site.
Heretofore, a patient needing to take blood samples and also needing to take injections required two separate devices if automated insertion was to be accomplished. In contrast, the present invention provides a lancet holder which is simulative in shape of a hypodermic syringe so that the holder can be used in an automatic injector, such as the type taught by the present invention, for automatic insertion of a lancet point into a selected tissue site.